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Table 1 Odds ratios for childhood leukaemias and lymphomas (conditional logistic regression)

From: Birth characteristics and the risk of childhood leukaemias and lymphomas in New Zealand: a case-control study

Variable

Categories

Cases,Controls*

Unadjusted OR (95% CI)

Adjusted OR (95% CI)

Cases, Controls*

Unadjusted OR (95% CI)

Adjusted OR (95% CI)

Leukaemias

 

Acute lymphoblastic leukaemia (ALL) †

 

Acute non-lymphoblastic leukaemia (ANLL) †

Parity

0‡

71,82

1.0

1.0

15,17

1.0

1.0

 

1

74,61

1.4 (0.9–2.2)

1.4 (0.9–2.3)

11,16

0.7 (0.2–2.0)

0.8 (0.2–2.6)

 

2

48,49

1.1 (0.7–1.9)

1.2 (0.7–2.0)

6,5

1.6 (0.4–6.2)

1.7 (0.4–7.8)

 

≥ 3

22,23

1.1 (0.5–2.1)

1.1 (0.6–2.2)

14,8

2.7 (0.7–9.7)

2.1 (0.5–8.0)

  

Continuous analysis§ 1.00 (0.85–1.16), p = 0.96

Continuous analysis§ 1.21 (0.93–1.58), p = 0.16

Social class||

I or II

45,44

1.0 (0.6–1.7)

-

6,12

0.5 (0.1–1.7)

-

 

III

79,66

1.2 (0.8–1.9)

-

16,19

0.6 (0.2–1.9)

-

 

IV

58,71

0.8 (0.5–1.3)

-

22,13

1.7 (0.6–4.7)

-

 

V or VI‡

74,75

1.0

-

19,19

1.0

-

  

Continuous analysis§ 0.97 (0.86–1.09), p = 0.60

Continuous analysis§ 1.23 (0.92–1.64), p = 0.17

Marital status

Married

250,241

1.3 (0.8–2.2)

1.5 (0.9–2.6)

55,59

0.7 (0.3–1.6)

0.8 (0.3–1.9)

 

Unmarried‡

28,37

1.0

1.0

16,12

1.0

1.0

Father's age (years)

<25

58,51

1.1 (0.7–1.8)

1.2 (0.8–1.9)

18,14

1.4 (0.5–4.1)

1.5 (0.5–5.0)

 

25–29‡

106,108

1.0

1.0

17,18

1.0

1.0

 

30–34

59,50

1.2 (0.8–1.9)

1.2 (0.8–1.9)

14,21

0.7 (0.2–2.1)

0.8 (0.2–2.9)

 

35–39

28,31

0.9 (0.5–1.7)

1.0 (0.6–1.9)

6,9

0.7 (0.2–2.9)

0.9 (0.2–4.5)

 

40+

6,17

0.4 (0.1–1.0)

0.4 (0.1–0.9)

9,2

4.5 (0.8–25.0)

4.7 (0.8–29.0)

  

Continuous analysis§ 0.97 (0.94–1.00), p = 0.10

Continuous analysis§ 1.03 (0.98–1.09), p = 0.23

Mother's age (years)

<20

29,23

1.2 (0.7–2.2)

1.4 (0.7–2.8)

7,11

0.6 (0.2–2.2)

0.5 (0.1–2.0)

 

20–24

91,107

0.8 (0.5–1.2)

0.8 (0.5–1.2)

24,17

2.4 (0.9–6.4)

3.7 (1.2–11.7)

 

25–29‡

104,97

1.0

1.0

17,24

1.0

1.0

 

30–34

41,34

1.2 (0.7–2.0)

1.1 (0.6–1.9)

14,14

1.5 (0.6–4.0)

1.8 (0.6–5.4)

 

35+

13,17

0.7 (0.3–1.5)

0.6 (0.2–1.3)

9,5

3.3 (0.7–14.3)

2.6 (0.5–13.3)

  

Continuous analysis§ 0.99 (0.96–1.03), p = 0.78

Continuous analysis§ 1.01 (0.95–1.08), p = 0.64

Urban status

Urban

175,185

0.9 (0.6–1.2)

0.9 (0.7–1.3)

51,50

1.1 (0.5–2.1)

1.2 (0.6–2.7)

 

Non-urban‡

101,91

1.0

1.0

20,21

1.0

1.0

Lymphomas

 

Non-Hodgkin's lymphomas †

 

Hodgkin's disease**

Parity

0‡

27,23

1.0

1.0

47,38

1.0

-

 

1

8,14

0.4 (0.1–1.3)

0.3 (0.1–1.2)

43,46

0.8 (0.4–1.4)

-

 

2

15,11

1.0 (0.4–2.9)

1.2 (0.4–3.6)

29,34

0.7 (0.3–1.3)

-

 

≥ 3

12,14

0.6 (0.2–1.9)

0.6 (0.2–1.8)

26,27

0.8 (0.4–1.6)

-

  

Continuous analysis§ 0.95 (0.75–1.20), p = 0.67

Continuous analysis§ 0.95 (0.82–1.10), p = 0.50

Social class||

I or II

12,14

0.8 (0.3–1.9)

-

25,17

1.6 (0.8–3.4)

1.4 (0.7–3.1)

 

III

21,22

0.8 (0.3–2.1)

-

38,41

1.0 (0.6–1.9)

1.0 (0.6–1.9)

 

IV

15,15

0.9 (0.4–2.2)

-

46,47

1.1 (0.6–1.9)

1.1 (0.6–2.0)

 

V or VI‡

22,19

1.0

-

44,48

1.0

1.0

  

Continuous analysis§ 1.06 (0.86–1.32), p = 0.58

Continuous analysis§ 0.92 (0.78–1.09), p = 0.35

Marital status

Married

67,74

0.4 (0.1–1.2)

0.5 (0.2–1.7)

152,150

1.4 (0.4–4.4)

1.2 (0.4–4.0)

 

Unmarried‡

12,5

1.0

1.0

5,7

1.0

1.0

Father's age (years)

<25

18,19

0.7 (0.3–1.6)

0.6 (0.2–1.4)

30,25

1.1 (0.6–2.2)

1.2 (0.6–2.5)

 

25–29‡

27,19

1.0

1.0

53,50

1.0

1.0

 

30–34

11,15

0.5 (0.2–1.3)

0.5 (0.2–1.5)

42,44

0.9 (0.5–1.6)

0.9 (0.5–1.7)

 

35–39

10,11

0.6 (0.2–1.7)

0.6 (0.2–1.7)

15,16

0.9 (0.4–2.0)

0.7 (0.3–1.7)

 

40+

5,7

0.5 (0.1–1.8)

0.5 (0.1–1.7)

13,18

0.7 (0.3–1.6)

0.6 (0.2–1.5)

  

Continuous analysis§ 0.98 (0.93–1.02), p = 0.35

Continuous analysis§ 0.96 (0.93–1.00), p = 0.07

Mother's age (years)

<20

13,7

1.4 (0.5–4.2)

0.9 (0.3–3.2)

6,12

0.5 (0.2–1.5)

0.9 (0.2–3.5)

 

20–24

24,22

0.9 (0.4–1.9)

0.7 (0.3–1.7)

58,53

1.1 (0.7–1.9)

1.1 (0.6–2.0)

 

25–29‡

25,22

1.0

1.0

50,50

1.0

1.0

 

30–34

12,18

0.5 (0.2–1.4)

0.5 (0.2–1.3)

24,29

0.8 (0.5–1.6)

0.7 (0.3–1.4)

 

35+

5,10

0.4 (0.1–1.4)

0.4 (0.1–1.3)

19,13

1.4 (0.6–3.4)

1.7 (0.6–4.5)

  

Continuous analysis§ 0.97 (0.92–1.03), p = 0.37

Continuous analysis§ 0.99 (0.94–1.04), p = 0.69

Urban status

Urban

47,54

0.7 (0.3–1.3)

0.6 (0.3–1.4)

94,96

0.9 (0.6–1.5)

0.9 (0.5–1.5)

 

Non-urban‡

31,24

1.0

1.0

63,61

1.0

1.0

  1. * The numbers are for cases and controls who contributed to the unadjusted analyses. In adjusted analyses, they vary depending on missing values in each variable in the model.
  2. † The confounders included for each variable are, (a) parity: social class; (b) social class: none; (c) marital status: mother's age; (d) father's age: social class; (e) mother's age: social class and, (f) urban status: social class.
  3. ‡ Reference category.
  4. § The result is the odds ratio that occurs as the variable increases by one unit, either by one year or one social class category (poorer) or one child, adjusted with confounders used in the categorical analyses.
  5. || Category I represents those of highest socio-economic level, while VI the lowest socio-economic level.
  6. ** The confounders included for each variable are, (a) parity: none; (b) social class: mother's age; (c) marital status: mother's age; (d) father's age: social class & parity; (e) mother's age: social class & parity and, (f) urban status: social class & parity.